4.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
commit 06eb061f48594aa369f6e852b352410298b317a8 upstream.
If blk_get_request() returns ENODEV then multipath_clone_and_map()
causes a request to be requeued immediately. This can cause a kworker
thread to spend 100% of the CPU time of a single core in
__blk_mq_run_hw_queue() and also can cause device removal to never
finish.
Avoid this by only requeuing after a delay if blk_get_request() fails.
Additionally, reduce the requeue delay.
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-mpath.c | 5 ++---
drivers/md/dm-rq.c | 2 +-
2 files changed, 3 insertions(+), 4 deletions(-)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -484,7 +484,6 @@ static int multipath_clone_and_map(struc
struct request **__clone)
{
struct multipath *m = ti->private;
- int r = DM_MAPIO_REQUEUE;
size_t nr_bytes = blk_rq_bytes(rq);
struct pgpath *pgpath;
struct block_device *bdev;
@@ -503,7 +502,7 @@ static int multipath_clone_and_map(struc
} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
pg_init_all_paths(m);
- return r;
+ return DM_MAPIO_REQUEUE;
}
memset(mpio, 0, sizeof(*mpio));
@@ -517,7 +516,7 @@ static int multipath_clone_and_map(struc
GFP_ATOMIC);
if (IS_ERR(clone)) {
/* EBUSY, ENODEV or EWOULDBLOCK: requeue */
- return r;
+ return DM_MAPIO_DELAY_REQUEUE;
}
clone->bio = clone->biotail = NULL;
clone->rq_disk = bdev->bd_disk;
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -280,7 +280,7 @@ static void dm_requeue_original_request(
if (!rq->q->mq_ops)
dm_old_requeue_request(rq);
else
- dm_mq_delay_requeue_request(rq, delay_requeue ? 5000 : 0);
+ dm_mq_delay_requeue_request(rq, delay_requeue ? 100/*ms*/ : 0);
rq_completed(md, rw, false);
}